As recording media on which various kinds of data are recorded, optical discs such as digital versatile discs (DVDs) or Blu-ray (registered trademark) discs (BDs) are used often.
As such optical discs, not only single-sided discs in which data is recorded only on a front surface but also double-sided discs in which data is recorded on both front and rear surfaces are considerably used.
In addition, for example, a data recording process on a BD is performed in units of clusters of 64 KB. However, defect clusters in which data recording or reading may not be performed due to various causes occur in some cases.
When a data recording process or a reproduction process is performed, such defect cluster regions are necessarily skipped for the processes. Data to be recorded in defect clusters is subjected to a process or the like in which alternative clusters are used. When such a cluster skipping process or an alternative cluster using process is performed, it is necessary to acquire defect cluster information.
Management information including the defect cluster information is recorded in, for example, a temporary disc management area (TDMA) set in an inner zone or an outer zone of a disc.
In the TDMA, for example, a temporary disc management structure (TDMS) including latest defect cluster information is additionally recorded as necessary whenever new data is recorded on a disc.
When data is subjected to a postscript process or a reproduction process, a latest TDMS is read, a defect cluster position is determined, and a recording or reproduction process is performed.
Also, the TDMA or the TDMS is management data unique to a recordable optical disc.
The TDMA or the TDMS is described in, for example, Patent Literature 1 (JP 2011-233230A).
However, so far, a TDMA has been generally configured to be set and recorded in units of areas of a disc. That is, in the case of a double-sided disc, defect information regarding a disc front surface is recorded in a TDMA of the front surface and defect information regarding a disc rear surface is recorded in a TDMA of the disc rear surface.
Accordingly, for example, when a TDMA on a disc front surface is not readable due to any cause, there is a possibility of defect information on the front surface not being obtainable and new data not being correctly recorded or reproduced.
That is, in the related art, a TDMS is not subjected to redundant recording and may be a single point of failure.